From the NES game "Snake Rattle 'n Roll." Little balls that are eaten to make your tail longer. Depending on the level in which they are found, nibbley-pibbleys have various means of locomotion, such as fish tails or helicopter blades. Nibbley-pibbleys can be orange, purple, or yellow; eating one the same color is better than eating one the color of the other snake, but the yellow ones are the best of all.